Issued annually since 1946/47, the Yearbook is the principal reference work of the United Nations, providing a comprehensive, one-volume account of the Organization's work. It includes details of United Nations activities concerning trade, industrial development, natural resources, food, science & technology, social development, population, environment, human settlements, children & legal questions, along with information on the work of each specialized agency in the United Nations family. The Yearbook is an indispensable guide to the UN.